The fact is that, as RealClimate has explained, we would need “an immediate cut of around 60 to 70% globally and continued further cuts over time” merely to stabilize atmospheric concentrations of CO2 – and that would still leave us with a radiative imbalance that would lead to “an additional 0.3 to 0.8ºC warming over the 21st Century.” And that assumes no major carbon cycle feedbacks kick in, which seems highly unlikely.

We’d have to drop total global emissions to zero now and for the rest of the century just to lower concentrations enough to stop temperatures from rising. Again, even in this implausible scenario, we still aren’t talking about reversing climate change, just stopping it — or, more technically, stopping the temperature rise. The great ice sheets might well continue to disintegrate, albeit slowly.

This doesn’t mean climate change is unstoppable — only that we are stuck with whatever climate change we cause before we get desperate and go all WWII on emissions. That’s why delay is so dangerous and immoral. For instance, if we don’t act quickly, we are likely to be stuck with permanent Dust Bowls in the Southwest and around the globe. I’ll discuss the irreversibility myth further below the jump.

Heck, the guy who debated me on The Economist‘s website conceded things are going so slowly, writing “The idea is that CCS then becomes a commercial reality and begins to make deep cuts in emissions during the 2030s.” And he’s a CCS advocate!!

Of course, we simply don’t have until the 2030s to wait for deep cuts in emissions. No wonder people who misunderstand the irreversible nature of climate change, like Nocera, tend to be far more complacent about emissions reductions than those who understand climate science.

The point of Nocera’s piece seems to be to mock Bill McKibben for opposing the idea of using captured carbon for enhanced oil recovery (EOR): “his answer suggests that his crusade has blinded him to the real problem.”

It is Nocera who has been blinded. He explains in the piece:

Using carbon emissions to recover previously ungettable oil has the potential to unlock vast untapped American reserves. Last year, ExxonMobil reportedthat enhanced oil recovery would allow it to extend the life of a single oil field in West Texas by 20 years.

McKibben’s effort to stop the Keystone XL pipeline is based on the fact that we have to leave the vast majority of carbon in the ground. Sure, it wouldn’t matter if you built one coal CCS plant and used that for EOR. But we need a staggering amount of CCS, as Vaclav Smil explained in “Energy at the Crossroads“:

“Sequestering a mere 1/10 of today’s global CO2 emissions (less than 3 Gt CO2) would thus call for putting in place an industry that would have to force underground every year the volume of compressed gas larger than or (with higher compression) equal to the volume of crude oil extracted globally by [the] petroleum industry whose infrastructures and capacities have been put in place over a century of development. Needless to say, such a technical feat could not be accomplished within a single generation.”

D’oh! What precisely would be the point of “sequestering” all that CO2 to extract previously “ungettable oil” whose emissions, when burned, would just about equal the CO2 that you supposedly sequestered?

Remember, we have to get total global emissions of CO2 to near zero just to stop temperatures from continuing their inexorable march toward humanity’s self-destruction. And yes, this ain’t easy. But it is impossible if we don’t start slashing emissions soon and stop opening up vast new sources of carbon.

For those who are confused on this point, I recommend reading the entire MIT study, whose lead author is John Sterman. Here is the abstract:

Public attitudes about climate change reveal a contradiction. Surveys show most Americans believe climate change poses serious risks but also that reductions in greenhouse gas (GHG) emissions sufficient to stabilize atmospheric GHG concentrations or net radiative forcing can be deferred until there is greater evidence that climate change is harmful. US policymakers likewise argue it is prudent to wait and see whether climate change will cause substantial economic harm before undertaking policies to reduce emissions. Such wait-and-see policies erroneously presume climate change can be reversed quickly should harm become evident, underestimating substantial delays in the climate’s response to anthropogenic forcing. We report experiments with highly educated adults–graduate students at MIT–showing widespread misunderstanding of the fundamental stock and flow relationships, including mass balance principles, that lead to long response delays. GHG emissions are now about twice the rate of GHG removal from the atmosphere.

GHG concentrations will therefore continue to rise even if emissions fall, stabilizing only when emissions equal removal. In contrast, results show most subjects believe atmospheric GHG concentrations can be stabilized while emissions into the atmosphere continuously exceed the removal of GHGs from it. These beliefs-analogous to arguing a bathtub filled faster than it drains will never overflow-support wait-and-see policies but violate conservation of matter. Low public support for mitigation policies may be based more on misconceptions of climate dynamics than high discount rates or uncertainty about the risks of harmful climate change.

But you have to remember that the climate changes so far, both observed and committed to, are minor compared with the business-as-usual forecast for the end of the century. It’s further emissions we need to worry about. Climate change is like a ratchet, which we wind up by releasing CO2. Once we turn the crank, there’s no easy turning back to the natural climate. But we can still decide to stop turning the crank, and the sooner the better.

Indeed, we are only committed to about 2°C total warming so far, which is a probably manageable — and even more probably, if we did keep CO2 concentrations from peaking below 450 ppm, the small amount of CO2 we are likely to be able to remove from the atmosphere this century could well take us below the danger zone.

But if we don’t reverse emissions trends soon, we will at least double and probably triple that temperature rise, most likely negating any practical strategy to undo the impacts for hundreds of years.

Further

Chanting "Kill the Bill, Not Us," over a hundred activists, many in wheelchairs, halted the only hearing on the Graham-Cassidy anti-health-care bill and were met with a response only the current cretins in power could conjure up: They were removed and arrested by police, Chairman Orrin Hatch told them to "shut up," and Bill Cassidy literally yawned through the turmoil. Democrat Ron Wyden called the spectacle "an abomination,” which aptly sums up the state of the Republic.